commit 11b037a0937148b943688c53b8ffa6f9c268209a
from: Stefan Sperling <stsp@stsp.name>
date: Wed Oct 09 13:26:34 2024 UTC

only preserve manually added ndp table entries in startup config

commit - a19921892669f5995d8ded4c0cf7238bf40e6213
commit + 11b037a0937148b943688c53b8ffa6f9c268209a
blob - cd771f24c72f9b2004e4a92ebb224c853e8c0b9b
blob + fb50b6294674355067d69e1886d059c6cfa3e2a1
--- ndp.c
+++ ndp.c
@@ -755,8 +755,6 @@ conf_ndp(FILE *output, char *delim)
 	for (next = rtdump->buf; next < rtdump->lim; next += rtm->rtm_msglen) {
 		rtm = (struct rt_msghdr *)next;
 		if (rtm->rtm_version != RTM_VERSION)
-			continue;
-		if (!(rtm->rtm_flags & RTF_HOST))
 			continue;
 		conf_ndp_entry(output, delim, rtm);
 	}
@@ -769,6 +767,19 @@ conf_ndp_entry(FILE *output, char *delim, struct rt_ms
 {
 	struct sockaddr_in6 *sin6;
 	struct sockaddr_dl *sdl;
+	static struct in6_nbrinfo *nbi;
+
+	/* Ignore entries which describe routes to networks. */
+	if (!(rtm->rtm_flags & RTF_HOST))
+		return;
+
+	/*
+	 * Ignore local entries. These correspond to addresses configured
+	 * on our network interfaces, and will already be preserved in case
+	 * of static IPs, and should not be preserved for dynamic IPs.
+	 */
+	if (rtm->rtm_flags & RTF_LOCAL)
+		return;
 	
 	sin6 = (struct sockaddr_in6 *)((char *)rtm + rtm->rtm_hdrlen);
 	in6_fillscopeid(sin6);
@@ -776,6 +787,15 @@ conf_ndp_entry(FILE *output, char *delim, struct rt_ms
 	if (sdl->sdl_family != AF_LINK)
 		return;
 
+	/* Skip table entries for addresses learned via NDP protocol. */
+	nbi = getnbrinfo(&sin6->sin6_addr, sdl->sdl_index, 0);
+	if (nbi == NULL || nbi->expire != 0)
+		return;
+
+	/*
+	 * This is a 'permanent' non-local entry. We assume this entry
+	 * was manually added to the NDP table, and should be preserved.
+	 */
 	fprintf(output, "%s%s %s", delim, routename6(sin6), ether_str(sdl));
 	if (rtm->rtm_flags & RTF_ANNOUNCE)
 		fputs(" proxy", output);